Which group of letters from the options provided will logically fill the blank (?) to complete the sequential pattern below?
PRT, OQS, NPR, ?

The correct option is MOQ.

To find the missing group of letters in the given sequential pattern, let us analyze the pattern followed by each letter position in the terms: PRT, OQS, NPR, ?

1. First letter of each term:
P → O → N → ?
Looking at their alphabetical positions:
P is 16th letter
O is 15th letter
N is 14th letter
Each step decreases by 1 position (16 - 1 = 15, 15 - 1 = 14).
Therefore, the next letter is 14 - 1 = 13th letter, which is M.

2. Second letter of each term:
R → Q → P → ?
Looking at their alphabetical positions:
R is 18th letter
Q is 17th letter
P is 16th letter
Each step decreases by 1 position (18 - 1 = 17, 17 - 1 = 16).
Therefore, the next letter is 16 - 1 = 15th letter, which is O.

3. Third letter of each term:
T → S → R → ?
Looking at their alphabetical positions:
T is 20th letter
S is 19th letter
R is 18th letter
Each step decreases by 1 position (20 - 1 = 19, 19 - 1 = 18).
Therefore, the next letter is 18 - 1 = 17th letter, which is Q.

Combining all three letters gives the group MOQ.